The Cornish were known as the South or West Welshmen.
As Wikipedia says:
The Anglo-Saxon Chronicles states that in 825 (adjusted date) a battle was fought involving the "Welsh", presumably those of Cornwall, and the Defnas (men of Devon). It only states:- "The Westwealas (Cornish) and the Defnas (men of Devon) fought at Gafulforda".
Westwealas clearly translates into old Saxon as West Welsh, meaning "West Romans/Foreignors."
There are, even today, many similarities between the Welsh and Cornish languages (numbers 1 to 10 are almost identicle).
So why am I apologising to the Cornish "Welshmen?"
Well, it was their patron Saint's day yesterday and, with one thing and another, I clean forgot to post greetings.
So, belatedly - I'd like to wish all Cornishmen in Kernow and further afield: